It's not that, though. It's that the game allows players to (gasp) imagine attacking China.
Perhaps the Chinese government are actually astute and realise that their ability to control the Chinese people is fragile and anything, even a fictional representation of insurrection could tip them over the edge into thinking 'hey, why not actually do this!?'
Flexible democracy is the best systems for a stable society, not a brittle authoritarian regime.
...and if they're feeling particularly angry
The Tao is like a glob pattern: used but never used up. It is like the extern void: filled with infinite possibilities.